DFT insight on stability, optoelectronic, and thermoelectric features of Na3XO (X = Cu, Ag) anti-perovskites: Promising materials for sustainable energy applications

Abstract

The structural stability, elastic, optoelectronic, and thermoelectric characteristics of anti-perovskites Na₃XO (X = Cu, Ag) have been studied using density functional theory (DFT). The computed formation energy suggests these materials' potential synthesis and thermal stability. The structural and elastic properties of Na₃CuO and Na₃AgO anti-perovskite compounds were analyzed using the Perdew–Burke–Ernzerhof (GGA-PBE) generalized gradient potential approximation. The electronic and thermoelectric properties are calculated using the TB-mBJ approximation. The materials are identified as direct narrow band gap semiconductors with band gaps of 0.65 and 0.43 eV. The analysis of two-dimensional charge density contours indicates that Na₃CuO and Na₃AgO have a mixed bonding character, as validated by the investigation of electron charge density. We analyzed the optical properties of Na₃CuO and Na₃AgO, including dielectric function, refractive index, absorbance, optical reflectivity, and energy loss, using photon energy up to 6 eV. The investigated thermoelectric characteristics demonstrate figure of merit (ZT) values of 0.58 and 0.56 at room temperature. Consequently, the analyzed anti-perovskites might address waste heat management requirements and sustainable energy solutions.